Gilead Study FTC-203 is an ongoing, open-label study designed to evaluate the antiviral activity of emtricitabine (FTC, Emtriva) in combination with other antiretroviral drugs in pediatric patients.

Study subjects received emtricitabine at a dose of 6 mg/kg/day up to a maximum dose of 200 mg a day; either an alcohol-free oral solution or capsules were used. If treatment naive, the patient also received stavudine (d4T, Zerit) and lopinavir/ritonavir (LPV/r, Kaletra); if treatment experienced and receiving lamivudine (3TC, Epivir), the patient was given emtricitabine in addition to his or her other antiretrovirals.

A total of 53 naive and 31 experienced patients were enrolled. The mean age was 6 years old; the median HIV RNA was 4.5 log with a CD4+ cell count of 826. Fifty-three percent of the study participants were female and 69% were black. The proportion of patients achieveing viral suppression at week 96 was as follows:

The only mutation to emerge among treatment-naive study subjects was M184V, the signature mutation of emtricitabine. No data on tolerability was presented.

The results of this study suggest that emtricitabine in pediatric patients achieves comparable antiviral activity to emtricitabine in adults. As noted in adult studies of lopinavir/ritonavir with lamivudine or emtricitabine plus a third nucleoside/nucleotide reverse transcriptase inhibitor, the most likely mutation to emerge with treatment failure is M184V.